Alternating-current commutator-machine.



No. 790,414. PATENTED MAY 23, 1905. G. WINTER & P. EIGHBERG.

ALTERNATING CURRENT GOMMUTATOR MACHINE.

APPLICATION FILED AUG. 24, 1903 Witness 5. L A,

UNITED STATES Patented May 23, 1905.

PATENT OFFICE.

GABRIEL IVINTER, OF VIENNA, AUSTRIA-HUNGARY, AND FRIEDRICH EICHBERG, OFBERLIN, GERMANY, ASSIGNORS TO GENERAL ELEC- T tIC COMPANY, A CORPORATIONOF NEIV YORK.

ALTERNATlNG-CURRENT COMMUTATOR-MACHINE.

SPECIFICATION forming part of Letters Patent No. 790,414, dated May 23,1905.

Application filed Angus. 24,1903. Serial No. 170,652.

To alt whom it may concern:

Be it known that we, GABRIEL WINTER,residingatVienna,Austria-Hungary,andFRIED- RICH EICI-IBERG, residing atBerlin, Germany, both subjects ofthe Emperor of Austria-Hungary, haveinvented certain new and useful Improvements in Alternating-CurrentCommutator-Machines, of which the following is a specification.

Our invention relates to alternating current machines of the commutatortype; and its object is to improve the commutation of such machines. Inmachines of this type, whether single phase or polyphase, it isadvantageous to prevent short-circuiting the coils of the armature,since the coils are always subject to a pulsating field which inducesheavy currents whenever a coil is shortcircuited. The ordinary meansemployed heretofore for avoiding short-circuiting a coil duringcommutation consists in employing brushes narrower than onecommutator-segment or if a parallel and independent windings are usedbrushes narrower than (it-1) segments. In a machine having two 2 poles,

in which there are p equipotential brushes distributed around thecommutator, it is customary to connect all these equipotential brushestogether. This arrangement, which is satisfactory in direct-currentmachines, gives rise to trouble in alternating-currentcommutating-machines, since it short-circuits the portion of thearmature-winding between each pair of equipotential brushes. In thewell-known series winding the portion of the armature-winding betweeneach pair of equipotential brushes consists of a single coil, and sincethis coil is subject to an alternating field heavy short-circuitingcurrents will flow.

Our invention consists in a novel arrangement of the commutator-brushesand their connections for multipolar alternating-current machines of thecommutator type. In accordance with our invention the equipotentialbrushes are not directly connected to each other, as in ordinaryarrangements; but each brush of one polarity is connected to a singlebrush of opposite polarity, either through a direct short circuit orthrough a source of potential, according as the armature-winding is tobe short-circuited or supplied with or delivering current. The brushesare thus connected in independent pairs, and short circuits of thearmature-winding between equipotential brushes are thereby avoided.

Our invention will best be understood by reference to the accompanyingdrawings, in which- Figure 1 shows diagrammatically our inventionapplied to a siX-pole two-phase armature. Fig. 2 shows a modification ofthe same applied to a four-pole winding. Fig. 3 shows a furthermodification, in which one phase is supplied with current and the othershort-circuited. Fig. i showsafurtherinodification, whereby the surfaceof the commutator is utilized to better advantage; and Fig. 5 showsdiagrammatically an arrangement adapted for a six-pole two-phase serieswinding.

Referring first to Fig. 1, the brushes (4 (Z are shown connected to thesecondary terminals of the transformer 02. Brushes of are connected tothe secondary terminals of the transformer 0, and the brushes 1) g areconnected to the secondary terminals of the transformer p. All theprimaries of these three transformers are connected to one phase 9. Theremaining brushes g, Z1, 2', n, it, and Zare similarly connected to thesecondaries of the transformers s t it, the primaries of which areconnected to the other phase, 9'. It will be seen that with thisarrangement all the brushes are connected in independent pairs, noelectrical connection existing between equipotential brushes, exceptthrough the armature-winding. Consequently no short circuits can beproduced.

It is of course not necessary that the primary windings of thetransformer should be separate. Thus Fig. 2 shows an arrangement inwhich a single primary supplies two secondaries, to which are connectedthe two pairs of brushes for one phase of a four-pole two-phase machine.

It is evident that the ratio of transformation of the transformers maybe varied as desired, as is indicated in Fig. 1. hen all of thesecondary winding of the transformer is cut out, the pair of brushesconnected thereto is short-circuited. Thus in Fig. 3 the brushescorresponding to one phase are short-circuited, while the brushescorresponding to the other phase are supplied with current. Theshort-circuited brushes are still maintained in independent pairs, as inthe first arrangement.

In order to utilize to greater advantage the surface of the commutator,each brush in the figures heretofore shown may be replaced by twobrushes separated by the width of a segment. Such an arrangement isshown in Fig. 4, which shows a two-phase four-pole machine correspondingto Fig. 2. The brushes for one phase are shown inside the commutator.All the brushes for the other phase are shown outside the commutator. Itwill be seen that these latter brushes comprise four pairs of brushesinstead of four brushes, thereby giving twice the bearing-surface of thecommutator obtained with the arrangement of Fig. 2. The brushes (2 f,which take the place of a single brush, are connected throughresistances to the brush a and to the brush g, respectively, and sincethere is the width of a commutatorsegment or a little more between thebrushes ef no short circuit can be produced. It will be seen that theconnection of the brushes in independent pairs is still maintained.

The equipotential brushes may be connected to each other, if desired,through variable resistance. Thus the brushes 6 f are shown connected toeach other through the variable resistance '0.

Referring to the brushes inside the commutator in this figure, it willbe seen that only a portion of the number heretofere shown are indicatedin this drawing. This number and arrangement of brushes is adapted for aseries winding. With a parallel winding a greater I number of brusheswould be used, as in the former figure.

Fig. 5 shows an arrangement for a six-pole machine adapted for use witha series winding. One pair of commutator-brushes is supplied with thepotential a, derived from the secondary of a series transformer T, theprimary of which is in series with the primary winding. Displaced ninetydegrees electrically from the first set of brushes is a second set.These are short-circuited on each other in independent pairs, as shown.

Although we have illustrated our invention diagrammatically, it will beunderstood that it is applicable to any multipolar alternatingcurrentmachine of the commutator type in which a plurality of equipotentialbrushes are distributed around the commutator.

What we claim as new, and desire tosecure by Letters Patent of theUnited States, is

1. In a multipolar alternating-current machine, a rotor-winding providedwith a commutator, two sets of equipotential brushes distributed aroundthe commutator, and conductors connecting each brush of one set with abrush of the other set so as to form a plurality ofindependently-connected pairs.

' 2. In a multipolar alternating-current machine, a rotor-windingprovided with a commutator, two sets of brushes, the brushes of each setbeing distributed around the commutator at equipotential points, and thebrushes of each set being of a width not greater than that of acommutator-segment, and conductors connecting each brush of one polaritywith a brush of the opposite polarity-so as to form a plurality ofindependently-connected pairs.

3. In a multipolar alternating-current machine, a rotor-winding providedwith a commutator, two sets of pairs of brushes, the pairs of each setbeing distributed around the commutator at equipotential points and thebrushes of each pair being of a width not greater than that of acommutator-segment and separated from each other by not less than thewidth of a segment, and conductors connecting each brush of one set witha brush of the other set so as to form a plurality ofindependently-connected pairs.

4. In a multipolar alternating-current machine, a rotor-winding providedwith a commutator, two sets of equipotential brushes distributed aroundthe commutator, conductors connecting each brush of one set with a brushof the other set so as to form a plurality of independently-connectedpairs, and means for interconnecting the independently-connected pairsthrough a variable resistance.

5. In a multipolar alternating-current machine, a rotor-winding providedwith a commutator, a plurality of sets of equipotential brushesdistributed around the commutator, and conductors connecting one brushof each set with one brush of each other set so as to form a pluralityof groups of independentlyconnected brushes.

In testimony whereof we have hereunto set our hands in presence of twosubscribing witnesses.

GABRIEL WINTER. FRIEDRICH EICHBERG. Witnesses as to Gabriel Winter:

ALVESTO S. HOGUE, Aueus'r FUGGER. Witnesses as to Friedrich Eichberg:

HENRY HASPER, WOLDEMAR HAUPT.

